You find net charge by subtracting the number of electrons from the number of protons (since protons are positive and electrons are negative). 9 - 10 = -1
Potential energy at top:
PE = mgh
PE = 40 x 9.81 x 12
P.E = 4,708.8 J
Kinetic energy at bottom:
KE = 1/2 mv²
KE = 1/2 x 40 x 10²
K.E = 2,000 J
P.E = K.E + Frictional losses
Frictional losses = 4708 - 2000
Frictional losses = 2708 J
The answer is D.
The heat capacity is given by the expression:
When the 
is measured in the calorimeter, we obtain a value, and since we know the mass of the material and we control the change in 
, we can then determine the specific heat "C" by simply remplazing in the expression.
Answer: 16N
Explanation:
According to coulombs law which states that the force of attraction between two charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. Mathematically,
F = kq1q2/r²
If two charges that are separated by one meter exert 1-N forces on each other, the equation will become
1 = kq1q2/1²
kq1q2 = 1 ... (1)
If the charges are pushed together so the separation is 25 centimeters, the force between them becomes,
F = kq1q2/0.25² (25cm converted to meters)
0.0625F = kq1q2 ... (2)
Dividing equation 1 by 2 to determine the force F on each charges, it becomes;
1/0.0625F = kq1q2/kq1q2
1/0.0625F = 1
0.0625F = 1
F = 1/0.0625
F= 16N
